U.S. patent number 5,782,840 [Application Number 08/800,607] was granted by the patent office on 1998-07-21 for snare cauterization surgical instrument assembly and method of manufacture.
This patent grant is currently assigned to Wilk & Nakao Medical Technology, Inc.. Invention is credited to Naomi L. Nakao.
United States Patent |
5,782,840 |
Nakao |
July 21, 1998 |
Snare cauterization surgical instrument assembly and method of
manufacture
Abstract
An improved snare cauterization instrument assembly is provided
with a plurality of fixed connecting strands that severably join
the web member to the cauterization loop to prevent the undesired
movement of the web to the distal end of the loop prior to
electrical activation and severing of the tissue sample. A method
of manufacturing the assembly employs a resilient, flexible
catheter as a tool to facilitate the placement of the web member on
the loop.
Inventors: |
Nakao; Naomi L. (New York,
NY) |
Assignee: |
Wilk & Nakao Medical
Technology, Inc. (New York, NY)
|
Family
ID: |
25178849 |
Appl.
No.: |
08/800,607 |
Filed: |
February 14, 1997 |
Current U.S.
Class: |
606/114; 606/110;
606/113 |
Current CPC
Class: |
A61B
18/14 (20130101); A61B 17/32056 (20130101); A61B
18/10 (20130101); A61B 2017/00287 (20130101); A61B
18/1492 (20130101); A61B 2018/00791 (20130101); A61B
2018/1407 (20130101); A61B 2018/141 (20130101); A61B
2018/00642 (20130101) |
Current International
Class: |
A61B
18/14 (20060101); A61B 17/32 (20060101); A61B
18/04 (20060101); A61B 18/08 (20060101); A61B
17/00 (20060101); A61B 017/24 () |
Field of
Search: |
;606/1,106,110,114,113,127,128,151,32,37,39,40,45-52 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dawson; Glenn K.
Attorney, Agent or Firm: Abelman, Frayne & Schwab
Claims
What is claimed is:
1. An improved endoscopic surgical snare cauterization instrument
comprising an electrically conductive cauterization loop and a
flexible web member, said loop having a cauterization section at
its distal end, said web member forming a capture pocket having a
mouth defined by said loop, said web member being joined to said
loop by a plurality of sliding connecting strands of thermoplastic
material, the improvement which comprises means for severably
securing at least three connecting strands at fixed positions along
the distal end of the cauterization loop.
2. The snare cauterization instrument of claim 1 where one of the
at least three fixed connecting strands is at the distal tip of the
loop and the positions of the other fixed connecting strands are
spaced at approximately equal distances from the distal tip on the
opposing arms of the loop.
3. The snare cauterization instrument of claim 1 where the at least
three fixed connecting strands are at spaced apart positions along
the cauterization section of the loop.
4. The snare cauterization instrument of claim 1 in which the at
least three fixed connecting strands are at spaced-apart positions
on the distal end of the loop that reaches cauterization
temperature.
5. The snare cauterization instrument of claim 1 where the means
for severably securing the connecting strands at the fixed
positions is a clamp.
6. The instrument of claim 5 where the clamp is metal.
7. The instrument of claim 5 where the clamp contacts at least one
connecting strand.
8. The instrument of claim 5 where the cross-section of the loop is
circular and the clamp is annular with an inside diameter
approximately equal to the diameter of the loop.
9. The instrument of claim 8 where the clamp has a longitudinal
parting line and tapered edges, and the clamp is bent to conform to
the surface of the loop and secure the clamp and at least one
connecting strand to the loop.
10. The snare cauterization instrument of claim 1 where the means
for severably securing each of the at least three connecting
strands at fixed positions along said loop is a corresponding
number of orifices in said loop through each of which orifices a
connecting strand is passed and secured against movement.
11. The snare cauterization instrument of claim 1 where the means
for severably securing each of the at least three connecting
strands at a fixed position along said loop is a corresponding
number of radial grooves in the surface of said loop, into each of
which grooves is a connecting strand wrapped and secured against
movement.
12. A method for recovering a selected portion of internal body
tissues of a patient with an endoscopic surgical snare instrument,
said instrument comprising an electrically conductive cauterization
loop connected to a source of electrical energy and a flexible web
member connected to said loop essentially around the circumference
thereof by a plurality of sliding connecting strands that are in
sliding contact with said loop and said web member is further
connected to said loop by at least three fixed connecting strands
at fixed positions along the distal end of said loop, said method
comprising the steps of:
passing the loop over the selected internal body tissues to be
removed so that the web member substantially surrounds said
selected internal body tissues in the form of a capture pocket;
drawing the distal end of said loop into closing contact around a
base region of said selected internal body tissues;
during said step of drawing and closing said loop, conducting an
electrical current through said loop to sever said selected
internal body tissues at said base region;
during said step of conducting an electrical current through said
loop, melting and severing said at least three fixed connecting
strands at fixed positions and any sliding connecting strands
intermediate said at least three fixed connecting strands along the
distal end of said loop;
withdrawing the loop and the severed selected internal body tissues
contained in the capture pocket of the web member; and
moving the unsevered sliding connecting strands along the opposing
sides of said loop toward the distal end of said loop to thereby
dispose said web member at the distal end of said loop.
13. The method of claim 12 where said melting and severing of said
sliding connecting strands and said at least three fixed connecting
strands occurs along about one-third the length of the loop as
measured from the distal end of said loop.
14. The method of claim 12 where the number of sliding connecting
strands lying between the at least three fixed connecting strands
at fixed positions is less than half of the total number of sliding
connecting strands that connect said web member to said loop.
15. The method of claim 12 where the number of sliding connecting
strands lying between the at least three fixed connecting strands
at fixed positions is less than 20% of the total number of sliding
connecting strands that connect said web member to said loop.
16. A method for joining a flexible web member to an electrically
conductive cauterization loop, where said web is connected to said
loop by a plurality of sliding connecting strands of thermoplastic
material that pass around said loop, the method comprising
severably securing at least three connecting strands formed from
thermoplastic material at fixed spaced apart positions along the
cauterization section at the distal end of said loop.
17. The method of claim 16 where the securing of said at least
three connecting strands is by engaging each of said at least three
connecting strands with a clamp to thereby fix their respective
positions along said loop.
18. An improved method for manufacturing a snare cauterization
instrument assembly comprising a flexible web member in the form of
a capture pocket joined to an electrically conductive cauterization
loop by a plurality of sliding connecting strands, the method
comprising the steps of
(a) inserting a flexible-catheter through the connecting strands
that are attached to, or which form the periphery of the web;
(b) passing one free end of the preformed cauterization loop
through the annular passageway of the catheter;
(c) positioning the connecting strands of the web on the catheter
so that they do not extend beyond the free ends of the loop;
(d) removing the catheter from the loop and the connecting strands,
while simultaneously maintaining the connecting strands and web in
a fixed position with respect to the loop;
(e) severably securing at least three spaced-apart connecting
strands to the loop at positions proximate the distal end of the
loop.
19. The method of claim 18 where the catheter is made from a
resilient flexible polymer having a low coefficient of
friction.
20. The method of claim 18 where the catheter is provided with a
tip member to facilitate the passage of the free end of the
catheter through the connecting strands.
Description
FIELD OF THE INVENTION
This invention relates to an improvement in a surgical instrument
assembly for use in snare cauterization operations.
BACKGROUND OF THE INVENTION
It is known from the disclosure of U.S. Pat. No. 5,486,182 issued
to Nakao and Wilk to separably attach a flexible web member that
forms a capture pocket to a conductive cauterization loop. The
assembled web and cauterization loop are adapted to pass through a
hollow sheath, which sheath and assembly form part of an endoscopic
instrument for use in snare cauterization operations. The
disclosure of U.S. Pat. No. 5,486,182 is incorporated herein in its
entirety by reference.
As further disclosed in U.S. Pat. No. 5,486,182 a preferred means
for separably joining the flexible web member, which can be a nylon
mesh or net material, to the cauterization loop is by a plurality
of nylon filaments or ringlets. These nylon filaments or ringlets
are melted when electrical power is transmitted to the
cauterization loop, thereby releasing the web which has been formed
into a pouch or capture pocket.
What I have found in using an instrument assembly in accordance
with the '182 patent is that when the cauterization loop was
withdrawn into the sheath to close the loop around the polyp or
other tissue to be severed, the strands of material connecting the
web to the loop and, in some instances, the material comprising the
web, moved along the loop and became concentrated at the distal end
of the loop. The web material was bunched together and could become
interposed between the polyp and the heated distal end of the
cauterization loop. The presence of numerous filaments or ringlets
by which the web was slidably joined to the loop also interfered
with, and made more difficult and time-consuming the transection of
the tissue. An additional problem encountered was the generation of
excessive smoke from the burning of the nylon strands which
impaired visibility through the endoscopic optical system.
It has also been found that the manufacture of snare cauterization
instrument assemblies is time-consuming because of the difficulty
of passing the connecting strands over the conduction wire
cauterization loop. This is particularly so where a purse string is
employed which itself must be woven through the web member.
It is therefore an object of this invention to provide an improved
assembly for use in snare cauterization operations in which the
flexible web forming the capture pocket does not become interposed
between the tissue to be severed and the heated distal end of the
cauterization loop.
It is another objective of the invention to provide means for
severably attaching the flexible web to the cauterization loop so
that the filaments or strands joining the web to the proximal ends
of the loop are limited in their movement toward the distal end of
the loop when the loop is closed around the tissue to be
severed.
It is yet another object of the invention to provide means for
severably securing the web of a snare cauterization assembly to the
cauterization loop so that the movement of the web in the direction
of the distal end of the loop is limited.
Another object of the invention is to provide means for attaching
the flexible web of a snare cauterization assembly to the
cauterization loop that will permit the web to be separated from
the loop only at the distal end of the loop, the proximal portion
of the web remaining attached to the loop in order to contain the
severed tissue sample in the capture pocket of the web.
It is another object of the invention to provide an improved method
for manufacture of snare cauterization instrument assemblies that
is easier, faster and therefore less expensive than the prior art
methods.
These and other objects of the invention will be apparent to those
of ordinary skill in the art from the description which
follows.
SUMMARY OF THE INVENTION
The improved instrument of the invention is intended for use in the
cauterization and collection of tissues, (e.g. polyps) that are
located in patients during endoscopic procedures. A snare
comprising a flexible web member is placed over the tissue to be
removed. The periphery of the web member is attached by a plurality
of sliding connecting strands to the electrically conductive
cauterization loop. Another group of at least three thermoplastic
connecting strands are secured to the distal section of the loop at
fixed positions. When an electric current is applied to the loop to
sever and cauterize the tissue, the distal end section of the loop
is raised to a cauterization temperature which is sufficient to cut
through the tissue and seal the site to substantially prevent
bleeding. The most distally attached thermoplastic connecting
strands are melted by the heat generated in the distal end of the
loop. Simultaneously, as the loop is closed, the desired tissue
specimen is severed and the remaining stump of internal tissue is
cauterized by the heat resulting from the current passing through
the loop. As the proximal end of the loop is withdrawn into a
sheath in the endoscope channel, the remaining sliding connecting
strands attached to the web member are moved to the distal end of
the loop, where the tissue sample is retained in the capture pocket
of the web member. The specimen remains in the capture pocket of
the web member, external to the endoscope tube during its removal
from the body. When the loop is again advanced distally from the
tip of the endoscope, the loop opens to thereby allow the specimen
to be removed from the web member. Alternatively, the web member
can be severed from the distal end of the loop after the assembly
is removed from the patient.
A flexible web member that is formed from a net or mesh material
and that is partially severably from a cauterization loop is
secured in position on the cauterization loop of a snare
cauterization assembly at a plurality of spaced apart locations on
the distal end of the loop. By securing the web at a plurality of
fixed positions, preferably at fixed positions located at about
one-third to one-quarter of the distance from the distal end of the
loop, that part of the web which is proximally displaced from the
fixed attachment points cannot move past the fixed points towards
the distal end of the loop.
In a preferred embodiment of the invention, the flexible web is
secured at three spaced-apart locations that are past the midpoint
of the loop toward the distal end of the loop. In a further
preferred embodiment, the flexible web is secured at a first
position at the extreme distal end or tip of the loop and at two or
more additional positions that are spaced at approximately equal
distances from the first position on the opposing arms forming the
loop.
The web can be severably joined directly to the loop at a plurality
of positions by strands that form a part of the web, or the web can
be joined by means of intermediate filaments or strands, each of
which filaments or strands are secured at one end to the loop and
at the other end to the web, and preferably to the periphery of the
web.
If the web further comprises a purse string to facilitate the
closing of the mouth of the web to form the capture pocket, the
connecting filaments or strands can be secured to the purse string
since the purse string passes through and engages the periphery of
the web throughout the distal section of the web. It will be
understood that even though the plurality of the filaments which
are fixed at one end to the distal end of the loop and at their
other end to the purse string function to restrict distal movement
of the web, they are not directly joined to the web material.
However, in a preferred embodiment of the improved snare
cauterization assembly, the purse string is eliminated entirely.
The elimination of the purse string greatly simplifies the
manufacture of the assembly and therefore also reduces the labor
and related costs. Since only the portion of the web at the -distal
end of the loop is severed from the loop, the tissue sample is
readily retained in the pocket formed by that portion of the web
that remains joined to the loop. As will be appreciated by one
familiar with the art, the severed tissue sample is sticky and once
contacted by the web capture pocket will not be dislodged after the
loop is closed and while the endoscope is withdrawn from the
body.
As used herein, "web connecting strand" means both a strand that
forms an integral part of the web that is in contact with the loop,
or a separate strand that extends between the web and the loop, or
between a purse string threaded through the web and the loop.
The means for severably securing the web connecting strands to the
cauterization loop can be mechanical, as by the use of clamps,
apertures or grooves in the loop, and the like. Combinations of
such mechanical means can also be used to secure the connecting
strands. Alternatively, the web connecting strands can be severably
secured to the loop at a plurality of positions using self-bonding
adhesive material or a separate adhesive material. As used herein,
the term "self-bonding adhesive" is defined to mean a material or
method that can be altered, as by the application of heat or a
solvent to become sufficiently tacky that it will form a bond with
the surface of the cauterization loop. Polymeric materials, when
heated to a temperature less than their decomposition or ignition
temperatures become thermoplastic with sufficient tackiness, or
adhesive properties, to bond to a dissimilar surface such as metal.
Numerous compositions that have been developed for commercial use
as hot-melt adhesives can be employed.
When the web has been severably joined to the loop at a plurality
of fixed positions at the distal section of the loop, the
connecting strands at the proximal end of web will not be able to
slide distally past the fixed positions that are closest to the
proximal end of the loop. The movement of the connecting strands at
the distal end of the web will also be limited so that the capture
pocket can be more easily maneuvered into proper position over the
polyp that is to be transected. For example, if the web is secured
so that one-quarter of the periphery of the web at the distal end
of the loop restrained from sliding, the remaining three-quarters
of the web can move distally.
By fixing the distal section of the web with respect to the loop,
there is also avoided the tendency of the web to bunch up in one
position on the loop in the event that it becomes necessary to
completely retract the assembly into the hollow sheath in order to
reposition the endoscope in the patient. Likewise, the movement or
repositioning of the extended loop and web during a procedure is
greatly facilitated.
When the loop and web are deployed at the surgical site of the
transection, for example, of a polyp, the proximal end of the loop
is withdrawn to tighten the distal end of the loop about the stem
of the polyp. Since the connecting strands of the web are severably
secured to the distal end of the loop at a plurality of positions,
the movement of the proximal end of the web member toward the
distal end of the loop is limited and neither the web nor
connecting strands can become interposed between the distal end of
the loop and the tissue to interfere with the procedure.
When the electrical current is transmitted through the loop to
sever and cauterize the tissue, the means by which the web is
secured at fixed positions to the loop are also severed, i.e.,
melted by the heat generated in the loop. However, because the
material of the connecting strands joining the web to the loop
either directly or indirectly constitutes a relatively small
volume, and it is melted quickly, the fumes generated are minimal
and do not interfere with the visualization of the surgical site
via the optical system in the endoscope.
Because of the sticky nature of the bodily fluids on the surface of
the tissue sample, the sample remains in contact with the inner
surface of the web capture pocket and will not fall out of the
pocket during egress of the endoscope from the body.
In accordance with a further embodiment of the invention, an
improved method of manufacturing the assembly of the invention is
provided. As will be known to those familiar with the art, the
cauterization loop is disposable, and is a preformed wire loop
having two free ends that are inserted into a connector. The
improved manufacturing method of the invention comprises the steps
of (a) inserting a flexible catheter through the connecting strands
that are attached to, or which form the periphery of the web; (b)
passing one free end of the preformed cauterization loop through
the annular passageway of the catheter; (c) positioning the
connecting strands of the web on the catheter so that they do not
extend beyond the free ends of loop; (d) removing the catheter from
the loop and the connecting strands, while simultaneously holding
the connecting strands and web in a fixed position with respect to
the loop; (e) securing at least three spaced-apart connecting
strands to the loop at positions proximate the distal end of the
loop.
The catheter used in the improved method is sufficiently flexible
to follow the contour of the preformed conductive metal wire loop
and strong enough to resist puncturing by the free end of the curve
loop. The exterior surface of the catheter is smooth with a low
coefficient of friction to facilitate sliding contact with the
connecting strands of the web. The catheter can be made of a
tetrafluoretheylene fluorocarbon polymer, such as TEFLON.RTM., or
other polymers and copolymers having similar properties. Suitable
catheters are commercially available.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A and FIG.1B are schematic partial side perspective views
showing two embodiments of a snare cauterization instrument
assembly of the prior art.
FIG. 2 is a schematic side elevational view, on an enlarged scale,
of another embodiment of a snare cauterization instrument assembly,
showing a pocket-defining web member on a loop of the prior
art.
FIG. 3A is a schematic perspective view, also on an enlarged scale,
of a modified snare cauterization instrument assembly, showing an
auxiliary loop attached at three points to a cauterization
loop.
FIG. 3B is a schematic perspective view of the instrument assembly
of FIG. 3A following a surgical procedure for recovery of a tissue
sample.
FIG. 4 is a schematic perspective view of portion of a loop
illustrating one means for clamping a web connecting strand at a
fixed position.
FIG. 5 is a perspective view of the clamp shown in FIG. 5 with the
loop shown in phantom.
FIGS. 6A and 6B are perspective views showing other embodiments for
practicing the method of the invention.
FIGS. 7A-D are schematic perspective views illustrating the
improved method for manufacturing the snare cauterization
assembly.
In the description of the figures which follow, like structural
components bear the same reference designations. FIG. 1A and 1B
show a capture web 20 in the form of a net fastened to loop 30.
Capture web 20 is thin and flexible and preferably made of
biologically inert flexible transparent synthetic resin or
polymeric material such as polyethylene or nylon. Prior to the
beginning of a snare cauterization operation, web 20 is disposed in
a closed, folded or contracted state, together with loop 30, in the
distal end of tubular member 50.
The web 20 is attached to loop 30 along web periphery 22 by a
plurality of sliding connecting strands 40 that pass around loop 30
and are tied or otherwise connected at their opposite ends to the
periphery 22 of web member 20.
FIG. 3A. shows a cauterization loop 30 with web member 20 joined at
three fixed positions by clamps 60 that secure three connecting
strands 42 to a distal end of the loop. This permanent attachment
of the sliding connecting strands at the proximal end of the web 20
to the loop 30 can be in the form of a ringlet, a wound thread that
is tied or joined at its free end by a spot of adhesive, etc.
Permanent attachment of the proximal sliding connecting strands 40
through the loop 30 prevents separation of capture and pocket 20
from loop 30 during the transection procedure and provides
additional assurance that the capture pocket will not become
detached from loop 30 while inside the patient.
As shown in FIG. 3B, after the electrical current is supplied to
the loop to sever the tissue sample, the severed tissue sample S is
contained in the web capture pocket 20. When the loop 30 is
withdrawn into tubular member 50, the sliding connecting strands 40
previously located at the proximal end of the loop are moved toward
the distal end of the loop. The fixed connecting strands 42 (and
any intervening sliding strands 40) have been melted by the
cauterization heat and only the three clamps 60 remain affixed to
the loop at its distal end portion. An opening 24 in the web exists
where the fixed and any intervening sliding connecting strands were
melted. However, because of the relatively small size of the
unattached portion of the web periphery and its tacky or sticky
surface, the sample S will not become dislodged from its position
inside the capture pocket.
As better shown in the enlarged view of FIG. 4, clamp 60 secures
connecting strand 42 to a fixed position on loop 30. In the
embodiment shown, clamp 40 is a slip annular ring having an inside
diameter when compressed that is approximately the same as the
outer diameter of loop 30 which has a circular cross-section. The
free end of connecting strand 42 is maintained in position by being
compressed between the clamp and surface of loop 30. In the
preferred embodiment shown, clamp 60 has beveled edges so that the
clamp will not engage or damage tissue with which it may come in
contact. Also shown in FIG. 4 adjacent to clamp 60 is a sliding
connecting strand that has been passed around the loop 30 and its
free end tied or otherwise joined so that it can move in sliding
contact with the loop. However, the presence of the fixed
connecting strand 42 precludes the further movement of sliding
connecting strands 40 in either direction along the loop 30. Thus,
that portion of the web which is proximal to the rear-most fixed
connecting strand 42 on each of the opposing arms of the loop 30
cannot move distally beyond the fixed strand. By this means, the
distal end of the loop 30 is kept free of an accumulation of web
material and/or connecting strands that might otherwise interfere
with the severing and cauterization of the tissue sample.
The fixing of at least three connecting strands at the distal end
of the loop 30 also serves the beneficial purpose of maintaining
the proper configuration of the distal end of the web member 20
during movement and positioning of the loop over the tissue sample.
While the number of fixed connecting strands to be secured and
their precise position is not critical, it is preferred that at
least three strands be so fixed, as by clamp members or other means
described below, and that the number of sliding strands
intermediate the fixed strands be kept to a minimum. In a preferred
embodiment, the number of sliding connecting strands lying between
the fixed connecting strands at the distal end of the loop is less
that 50% of the total number of sliding connecting strands employed
to join the web to the loop 30. In a most preferred embodiment, the
number of intermediate sliding connecting strands is no more that
about 20% of the total number of sliding strands.
There is shown in FIG. 5 a further enlarged view of one embodiment
of clamp 60 in its original expanded position prior to securing it
to a fixed position on loop 30 (shown in phantom.) As will be
understood by one of ordinary skill in the art, clamp 60 can be
fabricated from a malleable metal, or metal alloy, so that the
opening between split faces 64 and 65 permit the open clamp to be
easily passed over the loop. After a connecting strand 42 has been
placed between the clamp and surface of the loop, the clamp is
compressed, most conveniently with a tool adapted for this purpose
(not shown), until faces 64 and 65 are in touching alignment, or
very close proximity. As noted previously, the beveled surfaces 62
are desirable to eliminate rough leading edges.
Shown in FIG. 6A is a alternative means for securing connecting
strand 42 at a fixed position along the distal end of loop 30. An
opening 34 leads to an orifice 36 which passes through loop 30. A
connecting strand from the periphery 22 of web 20 passes through
the orifice and is secured from movement as by means of a knot,
adhesive, or the like at 44.
In the embodiment of FIG. 6B, loop 30 is provided with groove 38
into which the free end of connecting strand 42 is placed and
wrapped one or more times and then tied or adhesively bound to
secure the strand against movement. Other means will occur to those
skilled in the art for securing the several connecting strands at
fixed positions along the distal end of the loop 30.
It will also be understood by those of ordinary skill in the art
that the cauterization loop is heated to a sufficient temperature
to sever the tissue sample and cauterize the remaining surface at
its distal end. Since the fixed points of attachment of the
connecting strands must be severed by the heat generated, these
positions must be fixed within the distal region reaching
temperatures sufficient to melt the thermoplastic material from
which the connecting strands are made. Commercially available
cauterization loops or wires of the type useful in this invention
typically reach elevated temperatures at the distal end over a
distance which is from about one-quarter to about one-third of the
overall length of the loop.
In preparation for use of the snare cauterization instrument
assembly 10 of the invention as illustrated in FIGS. 1A-3,
cauterization loop 30 is expanded from a collapsed configuration
inside the distal end of sheath member 50 to the expanded
configuration shown in the drawings.
Pursuant to additional steps in the procedure, capture pocket of
web member 20 is opened during the expansion of cauterization loop
30 and the expanded loop is passed over a selected polyp or other
internal tissue agglomeration to be removed, so that web member 20
substantially surrounds the polyp. Cauterization loop 30 is then
closed by pulling it into the distal end of sheath member 50. The
closure of cauterization loop 30 around a base region of the polyp
while the cauterization loop is energized with electrical current
serves to sever the polyp at its base. Maintaining web member 20
surrounding the polyp during the cauterization procedure serves to
capture the severed polyp at the instant of its severance.
Loop 30 is further retracted into sheath member 50 upon the
termination of a cauterization operation. Web member 20 and the
captured internal body tissues remain outside of sheath member 50.
As the loop 30 is retracted the sliding connecting strands are
caused to move distally along the loop 30 by their contact with the
leading edge of sheath member 50.
In preferred embodiment, the distal end of web 20 is initially
connected to loop 30 by the at least three connecting strands in
fixed positions and a minimal number of intermediate sliding
connecting strands which are burned off or otherwise severed during
a cauterization operation, thereby leaving the capture pocket of
the web joined to loop 30 by the plurality of sliding connecting
strands at the proximal end of the web.
In the practice of the method of this invention, the web which
forms the capture pocket is prevented from moving along the
opposing arms of the loop to accumulate at the distal end of the
loop by securing several connecting strands at fixed positions
proximate the distal end of the cauterization loop. Thus, the
method contemplates recovering a selected portion of internal body
tissues of a patient with an endoscopic surgical snare instrument,
said instrument comprising an electrically conductive cauterization
loop connected to a source of electrical energy and a flexible web
member connected to said loop essentially around the circumference
thereof by a plurality of sliding connecting strands that are in
sliding contact with said loop and said web member further
connected to said loop by at least three connecting strands at
fixed positions along the distal end of said loop, said method
comprises the steps of:
passing the loop over the selected internal body tissues to be
removed so that the web member substantially surrounds said
selected internal body tissues in the form of a capture pocket;
drawing the distal end of said loop into closing contact around a
base region of said selected internal body tissues;
during said step of drawing and closing said loop, conducting an
electrical current through said loop to sever said selected
internal body tissues at said base region;
during said step of conducting an electrical current through said
loop, melting and severing said at least three connecting strands
at fixed positions and said sliding connecting strands intermediate
said at least three connecting strands along the distal end of said
loop;
withdrawing the closed loop and the web member containing the
severed selected internal body tissues in the capture pocket from
the surgical site; and
sliding the unsevered connecting strands along the opposing sides
of said loop toward the distal end of said loop to thereby dispose
said web member at the distal end of said loop.
The improved method for manufacturing the snare cauterization
assembly is schematically illustrated in FIGS. 7A-7D. As shown in
7A, a flexible catheter 70 having central orifice 72 is passed
through the connecting strands 40 attached to the web. As
previously described, it will be understood that the connecting
strands 40 can be the same filaments or fibers that comprise the
web, or connecting strands 40 can be separate elements that are
joined to the periphery of the web, or to a purse string, in the
event that one is used.
In a further preferred embodiment, a conical or rounded tip 74
having shaft 76 that is inserted in orifice 72 to facilitate the
threading of the catheter through the web connecting strands.
Alternatively, the end of the catheter that is to be threaded
through the free ends of the connecting strands can be shaped,
e.g., rounded, to facilitate its passage.
As shown in FIG. 7B, after the web is placed on the catheter, one
of the free ends of the wire cauterization loop 30 is pushed into
orifice 72 of catheter 70. The catheter and web are moved until
they are positioned on the loop, as shown in FIG. 7C. Thereafter,
as shown in FIG. 7D, the catheter 70 is removed from the loop 30 by
pulling on one of the free ends of the catheter, while at the same
time holding the web in a stationary position relative to the loop
30. Note in FIG. 7D the catheter 70 has been partially removed by
sliding it off the loop. The catheter can be reused. The use of the
catheter greatly reduces the time required for assembly, thereby
reducing the labor and related cost.
Once the web 20 is in the desired position on the loop, a plurality
of the connecting strands 40 can be severably secured to the distal
end of loop 30 in accordance with the methods described above.
Although the invention has been described in terms of particular
embodiments and applications, one of ordinary skill in the art, in
light of this teaching, can generate additional embodiments and
modifications without departing from the spirit of or exceeding the
scope of the claimed invention. Accordingly, it is to be understood
that the drawings and descriptions herein are proffered by way of
example to facilitate comprehension of the invention and should not
be construed to limit the scope thereof.
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